1. Field of the Invention
The present invention relates to a feed roller of a conveying device.
2. Description of the Related Art
Many image reading apparatuses that read and electrically process an image of a document and printing apparatuses that print an image now include a conveying device that conveys a sheet such as a document to be read or paper on which an image is printed. Such a conveying device includes a roller having a rubber attached to its surface in contact with the sheet, the roller rotating to convey the sheet. Such a roller can degrade its conveying performance because of a reduced friction force of the rubber as a result of repeated sheet conveying operations. Some rollers are thus configured so as to permit easy replacement of the rubber with the aim of achieving conveyance accuracy (see, for example, Japanese Patent Application Laid-open No. 2005-15095, Japanese Patent Application Laid-open No. 2003-89442, and Japanese Patent Application Laid-open No. 11-286340).
When a user of the conveying device replaces the rubber of the roller with a new one, however, he or she may not be able to replace the rubber appropriately, having the rubber distorted, cracked, or damaged during installation. When the surface of a core on which the rubber is attached is contaminated, even if the rubber itself does not have a defect, the rubber slips over the core, and resultant insufficient torque during conveyance may result in a conveyance fault.